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Hydrothermal (NN)-N-15-N-15 abundances constrain the origins of mantle nitrogen 期刊论文
NATURE, 2020, 580 (7803) : 367-+
作者:  Zhao, Steven;  Jang, Cholsoon;  Liu, Joyce;  Uehara, Kahealani;  Gilbert, Michael;  Izzo, Luke;  Zeng, Xianfeng;  Trefely, Sophie;  Fernandez, Sully;  Carrer, Alessandro;  Miller, Katelyn D.;  Schug, Zachary T.;  Snyder, Nathaniel W.;  Gade, Terence P.;  Titchenell, Paul M.;  Rabinowitz, Joshua D.;  Wellen, Kathryn E.
收藏  |  浏览/下载：14/0  |  提交时间：2020/05/13

Nitrogen is the main constituent of the Earth'  s atmosphere, but its provenance in the Earth'  s mantle remains uncertain. The relative contribution of primordial nitrogen inherited during the Earth'  s accretion versus that subducted from the Earth'  s surface is unclear(1-6). Here we show that the mantle may have retained remnants of such primordial nitrogen. We use the rare (NN)-N-15-N-15 isotopologue of N-2 as a new tracer of air contamination in volcanic gas effusions. By constraining air contamination in gases from Iceland, Eifel (Germany) and Yellowstone (USA), we derive estimates of mantle delta N-15 (the fractional difference in N-15/N-14 from air), N-2/Ar-36 and N-2/He-3. Our results show that negative delta N-15 values observed in gases, previously regarded as indicating a mantle origin for nitrogen(7-10), in fact represent dominantly air-derived N-2 that experienced N-15/N-14 fractionation in hydrothermal systems. Using two-component mixing models to correct for this effect, the (NN)-N-15-N-15 data allow extrapolations that characterize mantle endmember delta N-15, N-2/Ar-36 and N-2/He-3 values. We show that the Eifel region has slightly increased delta N-15 and N-2/Ar-36 values relative to estimates for the convective mantle provided by mid-ocean-ridge basalts(11), consistent with subducted nitrogen being added to the mantle source. In contrast, we find that whereas the Yellowstone plume has delta N-15 values substantially greater than that of the convective mantle, resembling surface components(12-15), its N-2/Ar-36 and N-2/He-3 ratios are indistinguishable from those of the convective mantle. This observation raises the possibility that the plume hosts a primordial component. We provide a test of the subduction hypothesis with a two-box model, describing the evolution of mantle and surface nitrogen through geological time. We show that the effect of subduction on the deep nitrogen cycle may be less important than has been suggested by previous investigations. We propose instead that high mid-ocean-ridge basalt and plume delta N-15 values may both be dominantly primordial features.


  
Transgressive overyielding in mixed compared with monospecific Scots pine (Pinus sylvestris L.) and oak (Quercus robur L., Quercus petraea (Matt.) Liebl.) stands - Productivity gains increase with annual water supply 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2019, 439: 81-96
作者:  Steckel, M.;  Heym, M.;  Wolff, B.;  Reventlow, D. O. J.;  Pretzsch, H.
收藏  |  浏览/下载：11/0  |  提交时间：2019/11/26
Allometry  Complementarity  Growth partitioning  Inter-annual climate variation  Mixing effect  Productivity  REFORM  Triplets  
Factors influencing overyielding in young boreal mixedwood stands in western Canada 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2019, 432: 546-557
作者:  Kweon, Deogkyu;  Comeau, Philip G.
收藏  |  浏览/下载：8/0  |  提交时间：2019/04/09
Young boreal mixedwood stands  Mixing effect  Overyielding  Shade tolerance  Species composition  Stand density  Tree size  Stress gradient hypothesis  
High diversity mixed plantations of Eucalyptus and native trees: An interface between production and restoration for the tropics 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2018, 417: 247-256
作者:  Amazonas, Nino Tavares;  Forrester, David I.;  Silva, Carina Camargo;  Alves Almeida, Danilo Roberti;  Rodrigues, Ricardo Ribeiro;  Brancalion, Pedro H. S.
收藏  |  浏览/下载：6/0  |  提交时间：2019/04/09
Atlantic Forest  Forest landscape restoration  High diversity mixed plantations  Large-scale restoration  Mixing effect  Native species timber  Sustainable forestry  Tropical forest restoration  Tropical reforestation  
Species and soil effects on overyielding of tree species mixtures in the Netherlands 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2018, 409: 105-118
作者:  Lu, Huicui;  Condes, Sonia;  del Rio, Miren;  Goudiaby, Venceslas;  den Ouden, Jan;  Mohren, Godefridus M. J.;  Schelhaas, Mart -Jan;  de Waal, Rein;  Sterck, Frank J.
收藏  |  浏览/下载：11/0  |  提交时间：2019/04/09
Niche complementarity  Productivity  Species mixing effect  Soil  Volume growth  
Impact of Grain Shape and Multiple Black Carbon Internal Mixing on Snow Albedo: Parameterization and Radiative Effect Analysis 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2018, 123 (2) : 1253-1268
作者:  He, Cenlin;  Liou, Kuo-Nan;  Takano, Yoshi;  Yang, Ping;  Qi, Ling;  Chen, Fei
收藏  |  浏览/下载：6/0  |  提交时间：2019/04/09
snow grain shape  snow albedo  black carbon  internal mixing  parameterization  radiative effect